The invention relates to a method for establishing conference connections in dial-operated telecommunication exchanges employing broadcast devices already provided in the exchange.
It has been known to offer, for example, to subscribers connected to a dial-operated teleprinter exchange the possibility of establishing broadcast and conference connections. During a broadcast connection the calling subscriber who is establishing the connection is able to send his information to a plurality of called subscribers, although the called subscribers participating in the broadcast are not able to transmit information back to the calling subscriber. During a conference connection, however, the participating called subscribers do not only receive the information transmitted from the calling subscriber, but can also themselves transmit information which is received both by the calling subscriber and by all the other called subscribers participating in the conference connection. Broadcast connections are established via a broadcast device provided in the exchange. In the event that conference connections are also to be possible, this device can be supplemented by an assigned conference switching device.
However, a few problems arise in connection with the establishment of broadcast and conference connections. Since in known exchanges the conference switching devices are either separate from the broadcast devices, and thus can be reached by different subscriber numbers, or are connected to the broadcast device by means of switching bridges, the calling subscriber can only establish either a broadcast connection or a conference connection.
Another problem consists in the fact that in a conference connection, the items of information transmitted from the called subscribers to the calling subscriber, who is establishing the conference connection, are received by all the subscribers participating in the conference connection. It is not possible for an item of information emanating from the calling subscriber to be transmitted just to one single member of the called subscribers participating in the conference connection, and neither is it possible to transmit an item of information emitted from one single member of the called subscribers participating in the conference connection merely to the calling subscriber.
An object of the invention is to provide a method for operating telecommunication exchanges which serves to avoid these disadvantages.
More particularly, another object of the invention is to provide the subscribers with the possibility that, although a broadcast connection has been established, they can make a change to conference connections, and within a conference connection can also change to different types of conference connections.